Extract PipeIOHandler class into a header and rename to wxWakeUpPipe.

No real changes to the class, just make it possible to reuse it outside of
Unix wxEventLoop code.

See #10258.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74338 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/unix/evtloop.h

@@ -19,11 +19,7 @@
 
 class wxFDIODispatcher;
 class wxUnixEventLoopSource;
-
-namespace wxPrivate
-{
-    class PipeIOHandler;
-}
+class wxWakeUpPipe;
 
 class WXDLLIMPEXP_BASE wxConsoleEventLoop
 #ifdef __WXOSX__
@@ -56,7 +52,7 @@ protected:
 private:
     // pipe used for wake up messages: when a child thread wants to wake up
     // the event loop in the main thread it writes to this pipe
-    wxPrivate::PipeIOHandler *m_wakeupPipe;
+    wxWakeUpPipe *m_wakeupPipe;
 
     // either wxSelectDispatcher or wxEpollDispatcher
     wxFDIODispatcher *m_dispatcher;